Heat exchanger

ABSTRACT

A heat exchanger with louvers twisted by a predetermined angle with respect to flat parts of fins and with louver passages formed between adjoining louvers, wherein step differences projecting out to the louver passage side are provided at the louvers. According to this, when cooling air flows through the louver passages, the flow of the cooling air is disrupted by the step differences and temperature boundary layers are destroyed, so the local heat conductivity is again raised at the locations of the step differences.

TECHNICAL FIELD

The present invention relates to a heat exchanger which is effectivewhen applied to a radiator etc. for heat exchange between cooling waterand air of an internal combustion engine.

BACKGROUND ART

The fins in a conventional heat exchanger have louvers. The edge effectof the louvers enables the heat conductivity of the fins to be improved.Further, by tilting the louvers with respect to the flat parts by apredetermined angle, the flow of the cooling air is changed to guide thecooling air to the louver passages between the adjoining louvers andthereby improve the heat conductivity of the fins (for example, seeJapanese Patent Publication (A) No. 2003-83690).

However, in the above conventional heat exchanger, if the louver pitchis shortened to further improve the performance, there was the problemthat the cooling air ended up no longer being guided to the louverpassages, the edge effect was not improved, and as a result the heatconductivity of the fins could not be improved.

DISCLOSURE OF THE INVENTION

The present invention, in consideration of the above points, has as itsobject the improvement of the heat conductivity of the fins withoutshortening the louver pitch.

To achieve the above object, in the present invention, there is provideda heat exchanger provided with a plurality of tubes through the insideof which an inside fluid is circulated and arranged stacked over eachother and fins arranged between the tubes and having flat partssubstantially parallel to the direction of circulation of the outsidefluid flowing between the tubes, a plurality of louvers twisted by apredetermined angle with respect to the flat parts being provided at theflat parts along the direction of circulation of the outside fluid andlouver passages being formed between the adjoining louver, characterizedin that when the direction along a predetermined angle is made thelouver width direction, a step difference projecting out to the louverpassage side is provided at an intermediate part of each louver in thelouver width direction.

According to this, when the outside fluid flows through the louverpassages, the flow of the outside fluid is disrupted by the stepdifference and the temperature boundary layer is destroyed, so at thelocation of the step differences, the local heat conductivity is againimproved. Therefore, it is possible to improve the heat conductivity ofthe fins without shortening the louver pitch.

Further, in the present invention, the step difference is provided atthe louver passage side positioned at the upstream side in the directionof circulation of the outside fluid in the louver passages positioned atthe two sides of the louvers.

According to this, the flow of the outside fluid is strongly disrupted,so the heat conductivity of the fins can be further improved.

Further, in the present invention, there is provided a heat exchangerprovided with a plurality of tubes through the inside of which an insidefluid is circulated and arranged stacked over each other and finsarranged between the tubes and having flat parts substantially parallelto the direction of circulation of the outside fluid flowing between thetubes, a plurality of louvers twisted by a predetermined angle withrespect to the flat parts being provided at the flat parts along thedirection of circulation of the outside fluid and louver passages beingformed between the adjoining louver, characterized in that when thedirection along a predetermined angle is made the louver widthdirection, a communicating passage for communicating the louver passagespositioned at the two sides of each louver is provided at anintermediate part of the louver in the louver width direction.

According to this, when the outside fluid flows through the louverpassages, the outside fluid passes through the communicating passageswhereby the development of temperature boundary layers is suppressed.Therefore, it is possible to improve the heat conductivity of the finswithout shortening the louver pitch.

Further, in the present invention, the communicating passages are longslits extending in the stacking direction of the tubes formed by makingcuts along the stacking direction of the tubes, then deforming the twosides of the cuts.

According to this, it is possible to form communicating passages withoutgenerating waste material.

Further, in the present invention, the heat exchanger may use finsformed to corrugated shapes so as to have a plurality of flat partsarranged along the direction of circulation of the inside fluid andcurved parts connecting the adjoining flat parts.

Below, the present invention will be able to be more sufficientlyunderstood from the attached drawings and the preferred embodiments ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a front view of a heat exchanger according to a firstembodiment of the present invention, while FIG. 1(b) is an enlarged viewof part A of FIG. 1(a).

FIG. 2(a) is a partially cutaway perspective view of the fins 3 of FIG.1, while FIG. 2(b) is an enlarged view of part B of FIG. 2(a).

FIG. 3(a) is a sectional view of the fins 3 of FIG. 1 seen from the tubestacking direction X3, while FIG. 3(b) is an enlarged view of part C ofFIG. 3(a).

FIG. 4(a) is a graph showing the local heat conductivity and averageheat conductivity of fins 3 in a heat exchanger according to a firstembodiment, while FIG. 4(b) is a graph showing the local heatconductivity and average heat conductivity of fins 3 in a conventionalheat exchanger.

FIG. 5 gives sectional views of principal parts showing modifications ofthe fins 3 in the heat exchanger according to the first embodiment.

FIG. 6 is a perspective view of fins 3 in a heat exchange according to asecond embodiment of the present invention.

FIG. 7 is a perspective view of fins 3 in a heat exchange according to athird embodiment of the present invention.

FIG. 8(a) is a partially cutaway perspective view of fins 3 in a heatexchange according to a fourth embodiment of the present invention,while FIG. 8(b) is an enlarged view of a part D of FIG. 8(a).

FIG. 9(a) is a sectional view of the fins 3 of FIG. 8 as seen from thetube stacking direction X3, while FIG. 9(b) is an enlarged view of apart E of FIG. 9(a).

BEST MODE FOR WORKING THE INVENTION First Embodiment

The present embodiment applies the heat exchanger according to thepresent invention to a radiator 1 for heat exchange between coolingwater of a running engine (internal combustion engine) and air so as tocool the cooling water. FIG. 1(a) is a front view of the radiator 1,FIG. 1(b) is an enlarged view of part A of FIG. 1(a), FIG. 2(a) is apartially cutaway perspective view of the fins 3 of FIG. 1, FIG. 2(b) isan enlarged view of part B of FIG. 2(a), FIG. 3(a) is a sectional viewof the fins 3 of FIG. 1 seen from the tube stacking direction X3, andFIG. 3(b) is an enlarged view of part C of FIG. 3(a).

As shown in FIG. 1, the radiator 1 has tubes 2 through the inside ofwhich engine cooling water flows, corrugated-shaped fins 3 bonded to theoutside surfaces of the tubes 2, header tanks 4 provided at the ends ofthe tubes 2 in the direction of circulation X1 of the cooling water(hereinafter referred to as the “cooling water circulation directionX1”) and communicating with the tubes 2, etc. Note that the enginecooling water corresponds to the inside fluid of the present invention.

The tubes 2 are made of metal (in the present embodiment, aluminumalloy). Cooling water passages through which the cooling water flows areformed inside them and are formed as flat shapes. Further, a pluralityof the tubes 2 are stacked over each other. The fins 3 are arrangedbetween the adjoining tubes 2. Cooling air is designed to be able toflow between the adjoining tubes 2. Note that the cooling aircorresponds to the outside fluid of the present invention.

The fins 3 promote the heat exchange between the cooling air and thecooling water and are comprised of a metal (in the present embodiment,aluminum alloy) and produced by press forming or rolling.

These fins 3, as shown in FIG. 2 and FIG. 3, have flat parts 3 a havingsurfaces substantially parallel with the direction of circulation X2 ofthe cooling air flowing between the tubes 2 (hereinafter referred to asthe “air flow direction X2”) and curved parts 3 b connecting theadjoining flat parts 3 a and are formed to corrugated shapes seen fromthe air flow direction X2. A plurality of these flat parts 3 a arearranged along the cooling water circulation direction X1.

Further, the flat parts 3 a are formed integrally with louvers 3 c bycutting and raising the flat parts 3 a. The louvers 3 c, when seen fromthe stacking direction X3 of the tubes 3 (hereinafter referred to as the“tube stacking direction X3”), are twisted from the flat parts 3 a by apredetermined angle θ1 (hereinafter referred to as the “twist angleθ1”). A plurality are provided at the flat parts 3 a along the air flowdirection X2. Further, louver passages 5 are formed between theadjoining louvers 3 c. The twist direction of the louvers 3 c positionedat the upstream side in the air flow direction X2 and the twistdirection of the louvers 3 c positioned at the downstream side in theair flow direction X2 differ. Note that the twist angle θ1 is, in thepresent embodiment, made 23°.

Here, when the direction along the angle θ1 is made the louver widthdirection X4, the intermediate part of each louver 3 c in louver widthdirection X4 is provided with a step difference 3 d extending in thetube stacking direction X3 and projecting out to the louver passage 5side.

One step difference 3 d is provided at each louver 3 c. The stepdifference 3 d is provided at the louver passage 5 side positionedupstream in the air flow direction X2 among the louver passages 5positioned at the two sides of each louver 3 c. Further, the bendingangle θ2 when viewing the step difference 3 d from the tube stackingdirection X3 is, in the present embodiment, made 90°.

Note that in the present embodiment, the fins 3 are made of aluminumalloy, the thickness t of the fins 3 is 0.05 mm, the length L of thelouvers 3 c in the louver width direction X4 (hereinafter referred to asthe “louver width L”) is 0.8 mm, and the amount of projection S of thestep differences 3 d is made 0.05 mm.

Further, the amount of projection S of the step differences 3 d ispreferably at least the thickness t of the fins 3. Further, when thelength of one period of the fins 3 formed in the corrugated shape is thefin pitch FP and the dimension of the cooling water circulationdirection X1 in the louvers 3 c is the louver pitch height HLP, it ispreferable that FP/HLP be 10 or less.

Next, the actions and effects of the present embodiment will beexplained.

FIG. 4(a) shows the change in the local heat conductivity of the fins 3according to the present embodiment, while FIG. 4(b) shows the change inthe local heat conductivity of the fins having configurations similar tothat described in Patent Publication 1.

As shown in FIG. 4(a), the upstream ends of the louvers 3 c in the airflow direction X2 become higher in local heat conductivity due to theedge effect. Next, when the cooling air flows through the louverpassages 5, the temperature boundary layers develop and the local heatconductivity gradually falls.

However, the radiator 1 of the present embodiment has step differences 3d projecting out to the louver passage 5 sides. By the cooling airstriking these step differences 3 d, the flow of the cooling air isdisrupted by the step differences 3 d and the temperature boundarylayers are destroyed, so at the locations of the step differences 3 d,the local heat conductivity again rises and the average heatconductivity is improved. Therefore, it is possible to improve the heatconductivity of the fins 3 without shortening the louver pitch.

Further, since the step differences 3 d are provided at the louverpassage 5 side positioned at the upstream side in the air flow directionX2, compared even with the case of providing the step differences 3 d atthe louver passage 5 side positioned at the downstream side of the airflow direction X2, the flow of the cooling air is strongly disrupted.Therefore, the heat conductivity of the fins 3 can be further improved.

Note that FIG. 5 shows modifications of the fins 3 of the presentembodiment and gives views of the step differences 3 d seen from thetube stacking direction X3.

FIG. 5(a) shows a step difference 3 d with a blunted bending angle θ2.FIG. 5(b) shows a step difference 3 d with a louver width L1 at one endand a louver width L2 at the other end made different. FIG. 5(c) shows aplurality of step differences 3 d provided at a louver 3 c .

Second Embodiment

A second embodiment of the present invention will be explained next.FIG. 6 is a perspective view of fins 3 in a heat exchanger according toa second embodiment.

The present embodiment is provided with, in place of the stepdifferences 3 d in the first embodiment, holes 3 e in the louvers 3 c.The other points are common with the first embodiment.

The holes 3 e pass through the louvers 3 c so as to communicate thelouver passages 5 positioned at the two sides. Further, the holes 3 eare oval in shape. A plurality are provided at the intermediate parts ofthe louvers 3 c in the louver width direction X4 and at the louvers 3 calong the tube stacking direction X3 (in this example, three). Note thatthe holes 3 e correspond to the communicating passages of the presentinvention.

According to this, when the cooling air flows through the louverpassages 5, part of the cooling air passes through the holes 3 e andflow to the adjoining louver passages 5, whereby the development oftemperature boundary layers is suppressed and therefore the average heatconductivity is improved. Therefore, it is possible to improve the heatconductivity of the fins 3 without shortening the louver pitch.

Third Embodiment

A third embodiment of the present invention will be explained next. FIG.7 is a perspective view of fins 3 in a heat exchanger according to thethird embodiment.

In the second embodiment, the holes 3 e were formed by punching, but inthe present embodiment, the holes 3 e are formed by cutting and raisingup parts of the louvers 3 c. Due to this, it is possible to form holes 3e without generating waste material. Note that the 3 f is a piece whichis cut and raised up.

Fourth Embodiment

A fourth embodiment of the present invention will be explained next.FIG. 8(a) is a partially cutaway perspective view of the fins 3 in aheat exchanger according to the fourth embodiment, FIG. 8(b) is anenlarged view of the part D of FIG. 8(a), FIG. 9(a) is a sectional viewof the fins 3 of FIG. 8 seen along the tube stacking direction X3, andFIG. 9(b) is an enlarged view of the part E of FIG. 9(a).

In the second embodiment, each louver 3 c was provided with a pluralityof holes 3 e to communicate the louver passages 5 positioned at the twosides of the louver 3 c, but the present embodiment each louver 3 c isprovided with one long slit 3 g extending in the tube stacking directionX3 so as to communicate the louver passages 5 positioned at the twosides of the louver 3 c. Note that the slits 3 g correspond to thecommunicating passages of the present invention.

The slits 3 g are formed as follows: That is, a cut is made in theintermediate part of each louver 3 c in the louver width direction X4along the tube stacking direction X3, then the two sides of the cut aredeformed. Due to this, it is possible to form the slits 3 g withoutgenerating any waste material.

Other Embodiments

In the above embodiments, the twist direction of the louvers 3 cpositioned at the upstream side in the air flow direction X2 and thetwist direction of the louvers 3 c positioned at the downstream side inthe air flow direction X2 were made different, but it is also possibleto make the twist directions of all of the louvers 3 the same.

Note that the present invention was explained in detail based onspecific embodiments, but a person skilled in the art could make variouschanges, modifications, etc. without departing from the claims and ideaof the present invention.

1. A computer-implemented method for communication within a network,said method comprising the steps of: transmitting a data packet as abroadcast signal from a first application node of a first subnetwork toa first gateway node of the first subnetwork; transmitting the datapacket as a point-to-point signal from the first gateway node to asecond gateway node of a second subnetwork; transmitting the data packetas a broadcast signal from the second gateway node of the secondsubnetwork to at least one application node of the second subnetwork;and simulating war games between two remote geographic sites.
 2. Thecomputer-implemented method as set forth in claim 1 further comprisingthe steps of: transmitting another data packet as a broadcast signalfrom the at least one application node of the second subnetwork to thesecond gateway node of the second subnetwork; transmitting the otherdata packet as a point-to-point signal from the second gateway node tothe first gateway node of the first subnetwork; and transmitting thedata packet as a broadcast signal from the first gateway node of thefirst subnetwork to the first application node of the first subnetwork.3. The computer-implemented method as set forth in claim 1 wherein saidtransmitting the data packet as a point-to-point signal is conductedacross an undedicated communication network.
 4. The computer-implementedmethod as set forth in claim 3 wherein the undedicated communicationnetwork is the Internet.
 5. (canceled)
 6. The computer-implementedmethod as set forth in claim 1 wherein the broadcast signals eachcomprise an Ethernet Protocol Data Unit.
 7. The computer-implementedmethod as set forth in claim 1 wherein the point-to-point signalincludes an IP address.
 8. The computer-implemented method as set forthin claim 1 further including the step of transmitting the data packet asa broadcast signal to a second application node of the first subnetwork.9. A system comprising: a first device for transmitting a data packet asa broadcast signal from a first application node of a first subnetworkto a first gateway node of the first subnetwork; a second device fortransmitting the data packet as a point-to-point signal from the firstgateway node to a second gateway node of a second subnetwork; and athird device for transmitting the data packet as a broadcast signal fromthe second gateway node of the second subnetwork to at least oneapplication node of the second subnetwork, the broadcast signals eachcomprising an Ethernet Protocol Data Unit.
 10. The system as set forthin claim 9 wherein said third device transmits another data packet as abroadcast signal from the at least one application node of the secondsubnetwork to the second gateway node of the second subnetwork; saidsecond device transmits the. other data packet as a point-to-pointsignal from the second gateway node to the first gateway node of thefirst subnetwork; and said third device transmits the data packet as abroadcast signal from the first gateway node of the first subnetwork tothe first application node of the first subnetwork.
 11. The system asset forth in claim 9 wherein said first device is a computer.
 12. Thesystem as set forth in claim 11 wherein the first gateway node convertsthe data packet from the broadcast signal to the point-to-point signalby adding an IP address to the broadcast signal.
 13. The system as setforth in claim 9 wherein said third means is a computer.
 14. The systemas set forth in claim 9 wherein said second means is an undedicatedintranet.
 15. The system as set forth in claim 9 wherein said firstdevice transmits the data packet as a broadcast signal form the firstapplication node to a second application node of the first subnetwork.16. An apparatus for simulating a war game, said apparatus comprising: afirst means for transmitting a data packet as a broadcast signal from afirst application node of a first subnetwork to a first gateway node ofthe first subnetwork; a second means for transmitting the data packet as.a point-to-point signal from the first gateway node to a second gatewaynode of a second subnetwork; and a third means for transmitting the datapacket as a broadcast signal from the second gateway node of the secondsubnetwork to at least one application node of the second subnetwork,said first, second, and third transmitting means simulating the war gamebetween two remote geographic sites.
 17. The apparatus as set forth inclaim 16 wherein said third means transmits another data packet as abroadcast signal from the at least one application node of the secondsubnetwork to the second gateway node of the second subnetwork; saidsecond means transmits the other data packet as a point-to-point signalfrom the second gateway node to the first gateway node of the firstsubnetwork; and said third means transmits the data packet as abroadcast signal from the first gateway node of the first subnetwork tothe first application node of the first subnetwork.
 18. A computerprogram product containing executable instructions for communicatingwithin a network, said product comprising: a first subnetwork having afirst application node and a first gateway node; and a second subnetworkhaving a second application node and a second gateway node, said firstapplication node transmitting a data packet as a broadcast signal tosaid first gateway node of said first subnetwork; said first gatewaynode transmitting said data packet as a point-to-point signal from saidfirst gateway node to said second gateway node of said secondsubnetwork, said second gateway node transmitting said data packet as abroadcast signal from said second gateway node of said second subnetworkto said second application node of said second subnetwork, the broadcastsignals each comprising an Ethernet Protocol Data Unit.
 19. The computerprogram product as set forth in claim 18 wherein said second applicationnode transmits another data packet as a broadcast,signal to said secondgateway node, said second gateway node transmits said other data packetas a point-to-point signal to said first gateway node, and said firstgateway node transmits said other data packet as a broadcast signal tosaid first and second application nodes.
 20. The computer programproduct as set forth in claim 18 wherein said first application nodetransmits said data packet as a broadcast signal to another applicationnode of said first subnetwork simultaneously to the transmission of saiddata packet to said first gateway node.